Science

Epic collision of galaxies hints at unraveling the mystery of missing matter

While the question of why so much matter is missing from the observable universe may sound like a dark matter problem, it gets even weirder.

There is another reason why scientists constantly run into vacancies when searching for all the matter in the universe. It is believed that a third of the baryonic matter (detectable) has not yet been detected. Presumably, this mass arose within a billion years after the birth of the universe, so it should be hidden from the Earth by several billion light years.

Astronomers who used NASA’s Chandra X-ray Observatory to observe the collision of galaxies in the Abell 98 cluster have now found what is likely evidence of missing matter. Although the evidence is sparse, Chandra’s recent observations show that the X-rays are coming from what may be missing matter at the center of two merging galaxies crawling towards each other in Abell 98, which is in the right zone, 1.4 billion light-years away. . Earth. Gaseous masses of hydrogen, helium and other undiscovered elements appear to be bound by X-rays.

Related: Chandra Space Telescope: Detecting the Unseen Universe

“Finding these strands of missing matter has proven to be an exceptionally difficult task, and only a few examples are known,” Arnab Sarkar, head of the Harvard and Smithsonian Center for Astrophysics (CfA), said in a statement. (will open in a new tab). “We’re excited that we’ve likely found another one.”

“We think this shockwave is an important discovery because our models predict such features should be there, but we haven’t seen them so far,” astrophysicist and CfA co-author Scott Randall said in a statement. “They are a key part of the early collision process that will eventually lead to cluster merging.”

Between galaxies and clusters of galaxies are monstrous filaments of hot gas known as the “warm-hot intergalactic medium” or WHIM. (will open in a new tab). Previously, it was assumed that an unknown substance is hiding in such regions.

WHIM, which has a mass of 400 billion suns, circulates with both hot and colder gases as predicted, with some of the hottest gases reaching nearly 36 million degrees Fahrenheit (19.9 million Celsius), likely , as a result of the collision. It is possible that the gas could also have been heated by the shock wave that occurred when gravity overcame the force and pulled the smaller cluster closer and closer to the larger cluster.

Shock waves are another thing that has been predicted before but has never been seen before these observations. Disturbed particles of matter will vibrate and crash into each other when the shock wave passes through them. (Thunder is a type of shock wave.) Galactic mergers, such as the huge merger in Abell 3667, are high energy and can span millions of light years.

Chandra could pick up WHIM in Abell 98 because its gas was highly heated by the shockwave. This shock wave is also especially rare because no one has ever noticed that this phenomenon occurs so early during the merger of two galaxies.

The study is described in an article accepted for publication in The Astrophysical Journal Letters. (will open in a new tab).

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